How do you size an oil-gas separator?

Answer 1

I can not give you a short easy answer. Crude oil is a complex mixture of hydrocarbons and no two fields have exactly the same composition. Also, the future production profile of gas, oil and frequently water is a forecast that is made individually for each field. Thus design of the separation system must be individually designed and tailored to the particular field and producing environment (offshore or onshore). However, certain general concepts apply. Water and gas separation require certain retention time to allow for gravity separation. The inflow rate of fluids, type of separators (vertical or horizontal), size and geometry will determine retention time. Baffles in the upper part of the separator wll help oil entrained in the gas to condense and not be produced with the gas. The oil leaving the separator may still contain gas, and a second or even a third stage of separation may be needed to completely degas the crude. Frequently, teams of production engineers compare different designs, to maximize processed oil and minimize cost. Further, for offshore processing, space limitations are very important. Because of the complexities of this subject, I would recommend you do further research. An excellent starting point is the Petroleum Engineering Handbook, Volume 3 which is available from the Society of Petroleum Engineers. See related link.

Answer 2

To size an oil-gas separator, you need to consider factors such as gas flow rate, oil flow rate, pressure drop, operating temperature, and acceptable oil carryover. Typically, this involves analyzing the properties of the fluid stream and using empirical correlations or specialized software to determine the appropriate vessel size and internals for efficient separation of oil and gas. Consulting with process engineers or utilizing separator sizing software can help ensure accurate design.